Question

Homeostasis is the process of maintaining a constant internal environment. However average body weight has been increasing worldwide, seemingly in contrast to the concept of homeostasis. Address the following issues using the textbook and optional outside sources (include citations). Opinions need to be supported by scientific facts.

1. What is the evidence that genetic factors influence body weight? What is the evidence that environmental factors contribute to body weight?
2. What are the benefits and risks of higher body weights?
3. What might account for the increase in body weight in the modern world?
4. What is a healthy body weight? How might it be maintained? Justify your answer.

Answer 1

Genetic Factors Influencing Body weight

· Single gene mutation - located in the leptin- melanocortin pathway.

· Syndromic obesity: phenotypes such as neurodevelopmental abnormalities, and other organ/system malformations

· More than 50 genes associated with obesity, most with very small effects

· Family health history is high risk of obesity-related diseases

Environmental Factors

Prenatal and early life influences, too much television watching, too little physical activity and sleep and our food and physical activity environment.

Insufficient sleep, (2) endocrine disruptors (environmental pollutants that interfere with lipid metabolism), (3) decreased variability in ambient temperature, (4) increased rates of smoking (5) increased use of medications that can cause weight gain (6) proportional increases in ethnic and age groups that tend to be heavier, (7) pregnancy at a later (8) epigenetic risk factors (9) assortative mating leading to increased concentration of obesity risk factors high blood pressure.

Benefits and risk of high body weight

Benefits: Good source for vitamins, Stores energy, Keeps us warm in bone-chilling weather, Protects the body from trauma,decreased incidence of rheumatoid arthritis.,protect from dementia, boost immune system, provide a better barrier against your external environment, shield you from physical harm.

Risk Factors: Heart disease and strokes, sleep apnea, Fatty liver disease, osteoarthritis, certain types of cancer, kidney disease

Increase of body weight in modern world.

Energy dense, cheap foods, labor-saving devices, motorized transport and sedentary work, high body fat tissue. Working and school conditions such as shift work, long hours and environments not conducive to physical activity can also complicate efforts to exercise, 10% population is obese at present.

Healty body weight and its maintenance

To gain proper body weight factors to be considered include age, muscle-fat ratio, height, sex, and body fat distribution, or body shape. Body mass index (BMI) is a common tool for deciding whether a person has an appropriate body weight. It measures a person’s weight in relation to their height.

Maintenance :Follow a healthy diet , physically active and limit the time spending physically inactive.